Carrier element for an IC module

ABSTRACT

A carrier element for an IC-module for incorporation into an identification card. The element includes a flexible carrier film supporting conductive leads and contact pads. A semi-conductor chip is electrically connected to the leads and pads. Cast resin surrounds the chip and carrier film, including the carrier pads, to form a solid carrier element capable of resisting mechanical stresses.

The present application is a continuation of U.S. patent applicationSer. No. 288,384, filed July 31, 1981, and now abandoned.

The invention concerns a carrier element for an IC module forincorporation into identification cards or similar data carriers.

The German patent application No. P 29 20 012 of the applicant describesan identification card with an embedded integrated circuit. For theproduction of the cards a so-called intermediate product (carrierelement) is employed which accepts the IC module with all its contactelements and can be produced as a self-contained unit independently ofthe production of the cards.

The carrier element, which can have a circular, box-type construction,is produced by using several films in a cold lamination process.

IC identification cards and other data carriers equipped with similarelectronic circuits have essential advantages compared to the usualcards for machine use, based on their greater storage capacity and theirability to participate actively in communication processes. Theseadditional advantages relative to usual identification cards quiteconsiderably increase the number of possibilities of application foridentification cards and open up a few entirely new areas ofapplication.

The production of IC identification cards in very large numbers isnecessary for the application of these types of identification cardsystems. It is therefore very important for the production of carrierelements, as well, to be able to apply a method which is economical forlarge numbers of items. It must be taken into consideration that thesemiconductor wafer and its connecting leads are exposed to great stressduring the production of the identification cards and their handling.

It must also be taken into consideration that in the case ofidentification cards of the above-mentioned type very different demandsare made in the various areas of application as far as the mechanicalstability, the durability, the resistance to environmental influencesand so on are concerned. Due to the possibility of active communicationthis also applies, of course, to the contact areas of the integratedcircuit as well as to the mechanical construction of the card.

Several contacting methods (e.g. galvanic, capacitive optical, etc.)have become known in the course of the development of IC identificationcards. The selection of one method over another for the production ofcarrier elements depends on the area of application of theidentification cards, the technical resources in production, the desiredconstancy of performance and other factors.

The problem of the invention thus consists in creating a carrier elementto be applied to identification cards or similar data carriers which canbe produced economically in large numbers, offers good protection forthe embedded semiconductor wafer and its connecting leads, and can beadjusted in production to various demands with respect to the durabilityof the cards and the type of contacting without any elaborate adaptingsteps.

The problem is solved according to the invention by casting asemiconductor wafer bonded on a foil, if necessary along with additionallayers, with a casting material to a compact unit of predeterminedthickness.

In the past many methods of contacting semiconductor wafers, i.e. ofproviding the tiny contact surfaces of the silicon crystal with contactsappropriate for subsequent use, have become known.

For example, the contact surfaces of the crystal are connected inso-called bonding automata with the connection legs of a contact spiderby fine golden wires, whereby the contact spider also serves as thecarrier of the semiconductor wafer.

Other methods use flexible material as a carrier for the wafers (seeDE-AS No. 24 14 297). The non-conductive material (e.g. in the form of asuper-8 film) is provided with windows at equal intervals, into whichwindows the self-supporting ends of a contact spider etched out ofconductive material extend. All the contact surfaces of the wafer areconnected in synchronism with the contact spider, which considerablyincreases the economic efficiency of the contacting method compared toolder methods.

The semiconductor wafers can also be mounted on a film without windowsin a similar manner.

The invention uses these established and rational production methods andthus attains an intermediate product which is particularly well suitedfor the production of carrier elements in large numbers and can beprocessed to all sorts of carrier elements without much effort andtaking into account the above-mentioned relevant requirements.

Due to the employment of the casting technique carrier elements with allsorts of properties (durability, contacting) can be realized without anyexpensive adapting steps. Furthermore, the semiconductor wafers andconnection leads are given excellent protection against mechanicalstress when the carrier elements are produced by the casting technique.

Further features and advantages of the invention can be seen in thedescription of the embodiments. The drawings show the following:

FIGS. 1a, 1b top view and cross-section of a semiconductor wafer, bondedon a foil

FIG. 2 a carrier element produced by the casting technique, suitable forindirect (contactless) contacting,

FIG. 3 a carrier element produced by the casting technique, suitable fordirect contacting,

FIG. 4 a semiconductor wafer attached to a through hole plated film,

FIGS. 5a, 5b cross-section and top view of a carrier element produced bythe casting technique by using the through hole plated film,

FIG. 6 a carrier element produced by the casting technique by using thethrough hole plated film and additional layers,

FIGS. 7a, 7b top view and cross-section of a semiconductor wafer, bondedon a foil when the bonding technique is being employed and

FIG. 8 the arrangement of FIG. 7 after the casting process

FIGS. 1a and 1b show a semiconductor wafer embedded in a film windowfrom the top and in cross-section. The semiconductor wafer 1, arrangedin a punched out window 2 of the film 3, is connected in the appropriateautomata with the ends of a contact spider 4 etched in a previousoperation. The transport of the film 3 during the various operationalphases can be carried out very precisely with the help of the perforatedholes 5 of the film.

A carrier element that can be produced very simply by using theintermediate product shown in FIGS. 1a and 1b is shown in FIG. 2.

The film 3 that is contacted with the semiconductor wafers 1 is directedto a casting unit 6. The two mold halves 6a and 6b are arrangedperpendicularly movable with respect to the film level. The casting unitis filled with an appropriate casting material via a feed channel 6c.The drain channel 8 prevents air pockets from forming in the castingunit during the casting process. Casting arrangements of this sort areknown, so that it is not necessary to go into detail here. The solidityof the finished carrier elements can be varied within wide limits by thechoice of the casting material.

The carrier element produced according to the representation in FIG. 2,which can be punched out of the carrier film as a compact unit 10 afterthe casting process, is suitable, for example, for indirect(contactless) accessing as by capacitive or optical means.

FIG. 3 shows a carrier element which is suitable for direct, galvaniccontacting.

For the production of this carrier element, the contact surfaces 4a areinitially coated before the casting process, so that bumps 7 are formedover the contact surfaces. The coating can consist of conductivematerial, which is, for example, galvanically applied to the contactsurfaces.

The coating can also consist of a non-conductive, elastic material (e.g.silicone), which is, for example, applied to the contact surfaces with awiper by using an appropriate mask. The arrangement thus provided withbumps 7 is finally directed back into an appropriate casting unit andpunched out of the carrier film as a compact unit 11 after the castingprocess. The bumps 7 can be formed in such a way that they extendslightly out of the cast block 11. In the case of this carrier elementthe contact surfaces are then on the same level as the cover filmsurface of the identification card after the carrier element has beenincorporated into the card.

If conductive material is used to form the bumps the carrier element issuitable for galvanic (direct) contacting.

If the bumps are formed out of non-conductive material, needles, forexample, can be used for contacting, which are directed through thenon-conductive material (e.g. silicone) onto the actual contact surfaces4a. This latter embodiment is advantageous insofar as the contactsurfaces of the carrier element are well protected from environmentalinfluences.

The above-mentioned embodiments use for their intermediate products anarrangement in which the semiconductor wafers are connected in aself-supporting way in punched out windows of a film with theappropriate connection leads. A disadvantage of this type of arrangementcan result in certain cases of application when as small an interval aspossible is required between the contact surfaces. In the case of theabove-mentioned arrangements the minimal distance of the contactsurfaces is determined by the size of the punched out window and thus bythe size of the semiconductor wafer. In order to obtain as small adistance as possible between the contact surfaces, it is also possibleto employ the arrangement shown in FIG. 4 as an intermediate product.

The contact surfaces 16 arranged on both sides of the film 12 areconnected with each other by a throughplating process. The semiconductorwafer 1 is applied to the film prepared in this way by the knowntechniques.

FIGS. 5a, 5b show the carrier element 15 produced by using theabove-mentioned intermediate product in cross-section and from the top.The casting process can be carried out similarly to the manner describedin connection with FIG. 2. As shown in FIG. 5b, the use of this latterintermediate product allows for a closely adjacent arrangement of thecontact surfaces 16.

FIG. 6 shows a carrier element for which a so-called through hole platedfilm is also used as an intermediate product. This arrangement ischaracterized by extremely great rigidity.

The carrier element consists in this case of a so-called through holeplated film 12, a spacing film 17 and a rearward cover film 18. Therearward cover film is provided with openings 19 which allow for theinflow and draining of the casting material in the casting unit. Thespacing film 17 has hollows 20 at regular intervals to accept thesemiconductor wafers. In the casting unit the hollow 20 is filled withan appropriate casting material. During the casting process a part ofthe casting mass also penetrates between the various films, so that thelatter are connected with each other particularly well. Between thesemiconductor wafers the various films 12, 17, 18 are connected witheach other in this example by an appropriate adhesive 25. In this waythe penetration of the casting mass into the interstices is made easierand simultaneously restricted. The restriction of the casting mass can,of course, also be achieved by pressing the film compound together onboth sides of the casting unit.

The rigidity of the arrangement can be further improved by using filmsmade of epoxy resin reinforced by glass fiber (GEP) and having the resinchosen for the production of the films be identical to the casting mass.In this case the casting mass also penetrates between the various films,which allows for the production of a carrier element with great rigidityand a compact construction.

FIGS. 7a and 7b show a further embodiment of an employable intermediateproduct for the production of carrier elements. The semiconductor wafer30 shown here is contacted by the so-called bonding technique. For thispurpose the carrier film 31 is initially punched out at regularintervals in such a way that the recess 32 with its finger-shapedextensions 32a as shown in the figures result. Then the carrier film 31is laminated over its entire surface with a film 33 of conductivematerial. According to known etching techniques the areas 34 are nowisolated from this film, which areas form the contact surfaces of thefinished carrier element.

The carrier film prepared in this manner is finally provided withsemiconductor wafers in commercial bonding automata. In the process onewafer 30 at a time is set into the recess 32 and attached to theconductive film 33 by aid of an appropriate adhesive 36. Then theconnection points of the wafer 30 are connected with the contactsurfaces 34 by fine golden wires 37.

FIG. 8 shows the carrier element 40 produced according to FIGS. 7a and7b, in which the recess 32 with its finger-shaped extensions 32a isfilled, for example, with an appropriate resin in a casting unit of theabove-mentioned kind. In the process the resin also penetrates into theareas 39 between the contact surfaces 34 that arose during the etchingprocess. The filling of the hollows does not necessarily have to becarried out in one of the casting units shown above in the case of thelatter arrangement. If the arrangement is sealed on one side, as shownin FIG. 8, for example with a self-adhesive film 38, the hollows can beeasily filled with a resin. The self-adhesive film, which is removedbefore further processing of the carrier element, simultaneously offersgood protection to the contact surfaces, in case the carrier elementsare to be stored for long periods.

What is claimed is:
 1. A carrier element for an IC-chip suitable forincorporation, as a unit, into a financial or identification card, saidcarrier element comprising:a carrier stratum having an aperture with aplurality of contact surfaces surrounding the aperture for externalcommunication to and from the carrier element; electrically conductiveleads connected to said contact surfaces and extending from said contactsurfaces into said aperture of said carrier stratum; an IC-chippositioned within said aperture and electrically connected to saidcontact surfaces of said carrier stratum by means of said electricallyconductive leads; and a cast, hardened body of resin completelysurrounding the IC-chip, said resin lying on both sides of the portionof said stratum adjacent said aperture and on the contact surfaces, saidbody of resin forming and defining the carrier element as a solidstructure having flat surfaces parallel to said stratum and having auniform thickness in a direction normal to said flat surfaces, saidcontact surfaces being so arranged in said resin body as to permitcommunication to and from said carrier element.
 2. A carrier elementaccording to claim 1 wherein said contact surfaces are embedded in saidresin body and are provided with projections of conductive materialwhich are approximately flush with one of said flat surfaces of saidelement for providing communication with galvanic electrodes applied tosaid contact surfaces.
 3. A carrier element according to claim 1 whereinsaid contact surfaces are embedded in the resin body and are providedwith projections formed of elastic, non-conductive material forproviding communication by galvanic electrodes penetrating saidprojections to said contact surfaces.
 4. A carrier element according toclaim 1 wherein said IC-chip is arranged in the center of the carrierelement.
 5. A carrier element for an IC-chip suitable for incorporation,as a unit, into a financial or identification card, said carrier elementcomprising:a carrier stratum having an aperture with a periphery, saidcarrier stratum further having a plurality of finger-like slotsextending from the periphery of said aperture into said stratum; anelectrically conductive film laminated to said carrier stratum andspanning said aperture and slots; contact surfaces formed out of saidelectrically conductive film but electrically isolated therefrom, saidcontact surfaces lying outside the periphery of said aperture, saidfinger-like slots extending from said aperture to said contact surfaces;an IC-chip positioned in the aperture of said carrier stratum andattached to said electrically conductive film; connection means in saidslots connecting said IC-chip to said contact surfaces; and casthardened resin in said aperture and slots, said resin surrounding saidIC-chip in said aperture and said connection means in said slots, saidresin being generally flush with the exposed surface of said carrierstratum.
 6. A carrier element according to claim 5 wherein said contactsurfaces are isolated from said film by spaced in said film and whereinsaid spaces are filled with said resin.